A picture of Jerome Murdough is held by his relatives at the home of his mother, Alma Murdough, in the Queens borough of New York. Jerome Murdough, a mentally ill, homeless former Marine arrested for sleeping in the roof landing of a New York City public housing project during one of the coldest recorded winters in city history, died last month in a Rikers Island jail cell.

NEW YORK — Jerome Murdough was just looking for a warm place to sleep on a chilly night last month when he curled up in an enclosed stairwell on the roof of a Harlem public housing project where he was arrested for trespassing.

A week later, the mentally ill homeless man was found dead in a Rikers Island jail cell that four city officials say had overheated to at least 100 degrees, apparently because of malfunctioning equipment.

The officials told The Associated Press that the 56-year-old former Marine was on anti-psychotic and anti-seizure medication, which may have made him more vulnerable to heat. He also apparently did not open a small vent in his cell, as other inmates did, to let in cool air.

“He basically baked to death,” said one of the officials, who all spoke on condition of anonymity because they were not permitted to discuss specifics of the case.

The medical examiner’s office said an autopsy was inconclusive and that more tests were needed to determine Murdough’s exact cause of death. But the officials, all with detailed knowledge of the case, say initial indications from the autopsy and investigation point to extreme dehydration or heat stroke.

Advocates for mentally ill inmates in New York say the death represents the failure of the city’s justice system on almost every level: by arresting Murdough instead of finding him help, by setting bail at a prohibitive $2,500 and by not supervising him closely in what is supposed to be a special observation unit for inmates with mental illnesses.

In a statement issued Wednesday, Department of Correction Acting Commissioner Mark Cranston called Murdough’s death “unfortunate” and reiterated that an internal investigation will look into the entire episode, “including issues of staff performance and the adequacy of procedures.”

Cranston also acknowledged that the temperature in Murdough’s cell was “unusually high” and said that action has been taken to fix mechanical problems to ensure safe temperatures, “particularly in areas housing vulnerable inmates.”

The department said it had addressed two contributing factors an outside consultant identified as causing the excess heat. It also said temperature checks immediately after the death revealed that several cells nearby were over 80 degrees.

Murdough’s 75-year-old mother, Alma Murdough, said she did not learn of her son’s death until the AP contacted her last week, nearly a month after he died. His public defender was told of the death three days after the inmate was found, the DOC said.

“He was a very lovely, caring guy,” said Murdough, adding that her son had bipolar disorder and schizophrenia and that she had not seen him in about three years.

“He had beer problems. Drinking beer. That was his downfall. Other than that, he was a very nice guy. He’d give you the shirt off his back.”

Family members say Murdough grew up in Queens and joined the Marine Corps right out of high school, doing at least one stint in Okinawa, Japan.

When he returned from the service, his family said, both his mental illness and thirst for alcohol became more pronounced, and he would often disappear for months at a time, finding warmth in hospitals, shelters and the streets.

“When he wanted to venture off, we let him, we allowed him to come and go,” recalled his sister, Cheryl Warner. “He always came back.”

Murdough’s criminal record included 11 misdemeanor convictions for trespassing, drinking in public and minor drug charges, said Ivan Vogel, a public defender who represented him at his arraignment on the trespassing charge.

According to the city officials, Murdough was locked alone into his 6-by-10 cinderblock cell at about 10:30 p.m. on Feb. 14, a week after his arrest. Because he was in the mental-observation unit, he was supposed to be checked every 15 minutes as part of suicide watch, they said. But Murdough was not discovered until four hours later, at about 2:30 a.m. on Feb. 15. He was slumped over in his bed and already dead.

When Murdough was found and his cell opened, his internal body temperature and the temperature in the cell were at least 100 degrees. Those temperatures could have been higher before he was discovered because the cell had been closed for several hours, the officials said.